It's an article of faith among Americans that we are overworked. We work long hours at our paid jobs, then come home and put in a long second shift. Mothers, in particular, perceive their combined work and child-care hours as extensive, leaving us starved for time -- a starvation that we sometimes assume our husbands don't face. One thing that keeps us from "leaning in" is that the demands of home make that impossible. But does the data bear that out?